Monday's news that starting quarterback Sean Mannion has suffered a knee injury and will miss this week's contest at BYU means that it is time to get to know the back-up quarterback in a hurry.

Mannion suffered an injury in the Washington State game, during a hand-off, Coach Riley told members of the media on Monday afternoon. He was able to finish the game and was seen walking the sidelines of practice on Monday with a 'slight limp.'

"I'm disappointed for young man," Riley said of Mannion. "He's invested a ton, but I told him that he'd be fine. I read about a guy who hurt his knee on the first play of the first game a few years ago, and Tom Brady is doing just fine."

The news of the injury is tough for the Beavers to swallow. Mannion played in 12 games last season, starting in 10. He threw for 3328 yards, 16 TD's and 18 interceptions. Through four games this year, he was 107-169-1358 yards, 7 touchdowns and four interceptions.

Starting this weekend in Provo will be redshirt junior Cody Vaz. He has seen limited game action, but has been impressive throughout spring and fall camp.

He played in five games as a redshirt freshman, completing 6 of 17 passes for 48 yards. In 2011, he did not see live game action, but due to an injury to then incumbent, Ryan Katz, he took most of the first team reps during the spring campaign.

In this year's spring game, Vaz completed 11 of 21 passes for 151 yards with one touchdown and one interception.

"We're going to go win the game with Cody. Cody is a good quarterback," Riley said Monday. "He has prepared for a long time and he's good and he'll be ready to go. He was in the thick of the competition a year ago and he was battling Sean for that spot then."

The upside to Vaz is that he has a much quicker release than Mannion and is also more mobile. The junior has taken plenty of snaps as the back-up quarterback for the past three seasons.

Vaz was a three-star prospect out of Stockton (Calif.) St. Mary's and was rated the #46 quarterback prospect in the nation by Rivals.com.

Join The Lodge for more inside discussion on the #10 Oregon State football team as they prepare to take on BYU this weekend.